1. Field of the Invention
The present invention relates to a photographing system for taking a picture of a moving object, such as a vehicle traveling on a road, especially, it relates to a photographing system that is capable of identifying or specifying a license plate or a make and model of the car, a face of a driver in the car, and so on.
2. Description of the Related Art
Camera systems for detecting or monitoring vehicles on the road, velocity monitoring equipment, which automatically detects a velocity of a moving vehicle and takes a picture of the vehicle, and license-plate reading equipment, which automatically recognizes the character on the license plate, are located on roads and highways, to monitor and regulate vehicles.
In the velocity monitoring equipment, for example, a Doppler radar system utilizing the Doppler-effect, detects a velocity of a moving vehicle, and a photograph of the vehicle is taken by cameras located above the road. Also, in the case of a pulse radar system, a pulsed high-frequency radio-wave is radiated, and the vehicle is photographed by a digital camera. The obtained image data is automatically transmitted to a traffic control center. On the other hand, in the license-plate reading equipment, a cameras takes a picture of a car on a lane in real-time to recognize a number of the license-plate, and the specified car is followed by other cameras located points. The velocity detecting equipment and the license-plate reading equipment are independently developed and are located at different positions.
In general, resolution required for an image depends upon an object to be photographed. For example, the recognition of the driver's face requires relatively high resolution compared to that of a license-plate. Whereas, identifying of the license plate requires higher resolution compared to the resolution required for recognition of the car configuration. Therefore, to always obtain an object image with high-resolution regardless of the object to be photographed, a special camera with a great number of pixels should be located to improve the resolution, so that the amount of image data to be transmitted increases.